The present invention relates to electro-sensitive movable fluids which flow by application of a direct-current-voltage, methods of using the movable fluids and motors using the movable fluids.
It is known that the characteristics of certain kinds of dielectric fluids vary when the dielectric fluids are subjected to electric fields. In case of liquid crystals, for example, when a voltage is applied to liquid crystal compounds in a liquid crystal phase (i.e., intermediate phase between a solid phase and a liquid phase), orientation properties of the compounds are controlled to thereby adjust light transmittance of the compounds, whereby visible images are formed. However, even if the liquid crystal compounds regulated by the orientation plates are placed in electric fields, they cannot flow freely because they are not liberated from the regulation.
Also, some fluids are known to exert an effect of variation of properties such as viscosity (electrical rheology effect or Winslow Effect).
The fluids exerting electrical rheology effect or Wien effect are generally colloidal dispersions wherein solid components, such as silica gel, cellulose, casein and polystyrene ion exchange resins, are mixed with insulating oils and dispersed in the oils, so that the storage stability of such fluids is low.
As lubricating oils for automobiles, those exhibiting electrical rheology effect have been proposed, but such lubricating oils are also heterogeneous and have a problem of low storage stability.
In Japanese Patent Laid-Open Publications No. 57274/1994 and No. 73390/1994, inventions of electrosensitive compositions wherein insulating oils are blended with specific fluorine compounds are disclosed.
The compositions disclosed in those publications are mixtures of insulating oils and fluorine compounds, and therefore they have a problem in the storage stability. Additionally, there is a worldwide tendency to avoid the use of fluorine compounds in recent years.
An object of the present invention is to provide an electro-sensitive movable fluid which flows upon application of a direct-current-voltage, a method of using the movable fluid and a motor using the movable fluid.
More particularly, the object of the invention is to provide an electro-sensitive movable fluid, wherein jet flow is induced by the electric energy of a direct-current-voltage applied to the movable fluid, said jet flow of the movable fluid being able to be taken out as mechanical energy such as rotational energy.
It is another object of the invention to provide an energy conversion method using the electro-sensitive movable fluid wherein the electric energy of a direct-current-voltage applied to the movable fluid is converted to energy in the other form.
It is a further object of the invention to provide a novel motor using the electro-sensitive movable fluid.
The electro-sensitive movable fluid of the invention comprises a compound having a conductivity "sgr" and a viscosity xcex7 located inside a triangle in a graph showing a relation between a conductivity "sgr", plotted as abscissa, and a viscosity xcex7, plotted as ordinate, of a fluid at the working temperature, said triangle having, as vertexes, a point P indicated by the conductivity "sgr"=4xc3x9710xe2x88x9210 S/m and the viscosity xcex7=1xc3x97100 Paxc2x7s, a point Q indicated by the conductivity "sgr"=4xc3x9710xe2x88x9210 S/m and the viscosity xcex7=1xc3x9710xe2x88x924 Paxc2x7s, and a point R indicated by the conductivity "sgr"=5xc3x9710xe2x88x926 S/m and the viscosity xcex7=1xc3x9710xe2x88x924 Paxc2x7s, or comprises a mixture of two or more kinds of compounds, said mixture being adjusted to have a conductivity "sgr" and a viscosity xcex7 located inside said triangle.
The electro-sensitive movable fluid may be an inorganic compound or an organic compound. When the electro-sensitive movable fluid is an organic compound, this organic compound preferably is a chain or branched, substantially dielectric fluid compound containing molecular end group composed of alkyl groups, outer ends of said groups inactivated by hydrogen atoms bonding to the carbon atoms, said molecular end groups being united by bonding to each other at the inner ends,
in which the bonding hand of each carbon atom for constituting the end groups with the sealed ends is bonded to at least one hetero atom and further linked to a straight-chain divalent hydrocarbon group, which may have a hetero atom and may have a branch, through the hetero atom, or is bonded to a divalent hydrocarbon group which may have a hetero atom or may have a branch.
When a voltage is applied between at least two electrodes arranged in the electro-sensitive movable fluid of the invention, the electro-sensitive movable fluid can be moved in the direction of one electrode to the other electrode.
Further, using the electro-sensitive movable fluid, the electric energy can be converted to energy of other form by a method comprising the steps of arranging at least one pair of electrodes in the electro-sensitive movable fluid, applying a voltage between the electrodes to form jet flow of the electro-sensitive movable fluid at a velocity corresponding to the applied electric energy, and converting fluid energy of the jet flow of the electro-sensitive movable fluid to mechanical energy capable of being taken out. In this case, the energy conversion using the electro-sensitive movable fluid can be controlled by a method comprising the steps of arranging at least one pair of electrodes in a container filled with the electro-sensitive movable fluid, applying a direct-current-voltage between the electrodes to convert electric energy to fluid energy of the electro-sensitive movable fluid by changing the applied direct-current-voltage in a range of 0.1 V to 10 kV to control the flow velocity and the flow direction of the electro-sensitive movable fluid in proportion to the applied direct-current-voltage, and converting the fluid energy of the movable fluid to mechanical energy capable of being taken out.
The first motor for electro-sensitive movable fluid (referred to as xe2x80x9cRE type ECF motorxe2x80x9d hereinafter, ECF: electro-conjugated fluid), which is preferably employed for the energy conversion, includes a container to be filled with an electro-sensitive movable fluid, a lid to close the container by being engaged with the open top of the container, a cylindrical rotor rotatable inside the fluid container around a rotating shaft borne by a shaft hole provided at the center of the lid and a bearing section provided at the center of the bottom of the container, plural first electrodes which are electrically connected with external electrode terminals through the rotating shaft at the upper part of the cylindrical rotor and arranged in the vertical direction on the surface of the cylindrical rotor, and second electrodes which are electrically connected with external electrode terminals through the rotating shaft at the lower part of the cylindrical rotor and arranged in non-contact with the first electrodes and in the vertical direction on the surface of the cylindrical rotor. The electro-sensitive movable fluid of the invention can drive the second motor for electro-sensitive movable fluid (referred to as xe2x80x9cSE type ECF motorxe2x80x9d hereinafter) other than the RE type ECF motor. The SE type ECF motor includes a cylindrical container to be filled with the electro-sensitive movable fluid, a lid of the container and a vane rotor, vanes of which detect motion of the movable fluid induced by application of a voltage to thereby rotate the rotor. The cylindrical container is provided with slits where the electrodes are arranged, and from the slits at least one pair of electrodes extend along the inner wall surface of the container.
As described above, the RE type ECF motor includes a container to be filled with an electro-sensitive movable fluid, a lid to close the container by being engaged with the open top of the container, a cylindrical rotor rotatable inside the container around a rotating shaft borne by a shaft hole provided at the center of the lid and a bearing section provided at the center of the bottom of the container, plural first electrodes which are electrically connected with first external electrode terminals through the rotating shaft at the upper part of the cylindrical rotor and arranged in the vertical direction on the surface of the cylindrical rotor, and second electrodes which are electrically connected with second external electrode terminals through the rotating shaft at the lower part of the cylindrical rotor and arranged in non-contact with the first electrodes and in the vertical direction on the surface of the cylindrical rotor. In the case of this motor, when a direct-current-voltage is applied between the first and second electrodes, jet flow of the electro-sensitive movable fluid is produced in the fluid container, whereby the rotor can be rotated together with the electrodes.
When a certain kind of dielectric fluid (i.e., xe2x80x9celectro-sensitive movable fluidxe2x80x9d of the invention) is subjected to an electric field, an electric force is generated in the fluid owing to the nonuniformity of electric conductivity and dielectric constant inside the fluid. In the direct current field, the Coulomb force acting on space charge dominates the dielectrophoretic force. The Coulomb force causes hydrodynamic instability, resulting in occurrence of convection of the electro-sensitive movable fluid or a secondary motion of the fluid. These phenomena are called xe2x80x9celetrohydrodynamic (EHD) effectsxe2x80x9d.
The present inventors have found that the electric energy can be readily converted to mechanical energy utilizing the EHD effects and succeeded in specifying a dielectric fluid capable of exerting the EHD effects. That is, the electro-sensitive movable fluid of the invention inherently is a dielectric fluid, but when the movable fluid is subjected to an electric field, electric current is brought about, though it is very small. When a direct-current-voltage is applied to the electro-sensitive movable fluid as described above, the movable fluid is moved owing to the EHD effects, whereby jet flow of the movable fluid is generated. The intensity (or rate) of the jet flow varies with the applied direct-current-voltage. Therefore, when the motion (jet flow) of the electro-sensitive movable fluid is captured and taken out, the electric energy can be utilized as mechanical energy transformed from the electric energy.
The present inventors consider that the motion of the electro-sensitive movable fluid in the invention is owing to the EHD effects. This means that the present inventors consider that the phenomenon occurring in the invention can be related with the xe2x80x9cEHD effectsxe2x80x9d, but they do not conclude that the phenomenon occurring in the invention is owing to the xe2x80x9cEHD effectsxe2x80x9d.